This application claims the priority of Germany Application No. 196 51 492.4-43, filed in Germany on Dec. 11, 1996, the disclosure of which is expressly incorporated by reference herein.
This invention relates to an effective, reliable device with a simple and compact design for removing NO.sub.x from exhaust.
Emission of nitrogen oxides (NO.sub.x) from internal combustion engines constitutes a significant environmental burden. While gasoline engines with three-way catalytic converters, operated with a fuel-air mixture of lambda=1, often conform to current regulations, Diesel and lean-mix engines, which consume less fuel because of the large quantity of used air during combustion pose a unique problem. Special NO.sub.x removal is necessary; so-called Denox catalytic converters are used for this purpose but they can only achieve a 50% maximum degree of conversion or removal.
It is therefore an object of the invention to provide an effective and reliable device with a simple and compact design for more efficiently removing NO.sub.x from exhaust. It is also an object of this invention to provide a method using the device.
This goal is achieved according to the invention by a device with a porous absorbent body saturated with a liquid alkaline electrolyte for absorbing NO.sub.x as nitrate and nitrite and electrodes for electrochemical decomposition of nitrate and nitrite to form nitrogen.
Absorption of NO.sub.x to form nitrate and nitrite takes place in the device according to the invention, followed by electrochemical decomposition of the nitrate and/or nitrite. NO.sub.x consists essentially of NO and NO.sub.2. With NO.sub.2 and nitrate, the following reactions take place in the device according to the invention: